JPWO2019021390A1 - Method for manufacturing metal member - Google Patents

Abstract

The manufacturing method of the metal member 13 includes a modeling step of manufacturing the three-dimensional object 11 made of metal by additive manufacturing by stacking and coupling a plurality of layers in the stacking direction DL. The three-dimensional model 11 includes a metal member 13 having an overhang portion 14, and a plurality of supports 12 that support the overhang portion 14 and that are integral with the metal member 13. The support 12 is in contact with the metal member 13 only at the tip of the support 12 in the stacking direction DL. The cross-sectional area of the tip portion of the support 12 is smaller than the cross-sectional area of other portions of the support 12.

Description

  The present invention relates to a method for manufacturing a metal member, which manufactures the metal member by additive manufacturing, which is also called 3D printing.

  In 3D printing, a three-dimensional object is manufactured by stacking a plurality of layers in a stacking direction and combining them. In many methods of 3D printing, if the final product you want to obtain contains an overhang, that is, a part that floats in the air, a support (also called a support material) that supports the overhang is used together with the product. Manufactured. Then, after the three-dimensional object including the product portion and the support portion is manufactured, the support is removed from the three-dimensional object. For example, Patent Document 1 discloses a device that removes a support material from a modeled object using a water jet.

JP, 2011-5666, A

  When the three-dimensional object is made of resin, a method is known in which the support is formed of a resin material different from that of the overhang portion, and the support is dissolved in a liquid and removed after the three-dimensional object is manufactured. If the three-dimensional object is made of metal, such a method cannot be adopted and it is necessary to physically remove the support. However, if many supports are included in the three-dimensional object, it is not possible to remove all the supports in a short time. In particular, when the three-dimensional object is made of metal, the strength of the support is higher than that when it is made of resin, and therefore the support cannot be easily removed. Furthermore, if the support is inside the hollow, it is more difficult to remove the support because the support is hidden by the hollow.

  Then, one of the objectives of this invention is to provide the manufacturing method of a metal member which can reduce the burden required for support removal.

  One embodiment of the present invention is a method for manufacturing a metal member, including a modeling step of manufacturing a three-dimensional object made of metal by additive manufacturing by stacking a plurality of layers in a stacking direction and combining them. The molded article includes a metal member having an overhang portion, and a plurality of supports that support the overhang portion and that are integral with the metal member, and the support includes only a tip portion of the support in the stacking direction. A method for manufacturing a metal member is provided, which is in contact with the metal member and has a cross-sectional area of a tip portion of the support smaller than a cross-sectional area of another portion of the support. The cross section means a cross section orthogonal to the stacking direction, and the cross sectional area means the area of the cross section perpendicular to the stacking direction. The method for manufacturing the metal member may further include a breaking step of breaking the support by vibrating the three-dimensional object with a support removing device.

  According to this structure, a metal three-dimensional molded object is manufactured by stacking and coupling a plurality of layers in the stacking direction. The three-dimensional model includes a metal member having an overhang portion and a plurality of supports that support the overhang portion. The support is an integral part of the metal member, which is made of the same metal material as the metal member. The support contacts the metal member only at the tip of the support in the stacking direction. The cross-sectional area of this tip is smaller than the cross-sectional area of the rest of the support. In other words, the strength of the tip of the support is lower than the strength of the rest of the support.

  When the three-dimensional object is vibrated, each support vibrates together with the metal member, and stress is generated in each part of the support. The tip of the support is the weakest of the supports. When the stress generated at the tip of the support exceeds the strength of the tip of the support, the tip of the support breaks. That is, the weakest tip of the support breaks first and the support is cut from the metal member. Therefore, each support can be cut from the metal member only by vibrating the entire three-dimensional object. This can reduce the burden required to remove the support.

  In this embodiment, at least one of the following features may be added to the method for manufacturing the metal member.

  At least a portion of the support has a cross section whose width is greater than its thickness.

  According to this structure, the thickness of the cross section of the support is smaller than the width of the cross section of the support. That is, the support is thin in the thickness direction and easily bends in the thickness direction of the support. When the three-dimensional object is vibrated, the support alternately repeats deformation and restoration in the thickness direction. This makes it possible to apply a repeated load whose size and direction change regularly to the support, and to reliably break the tip of the support.

  The width of the cross section of the support and the thickness of the cross section of the support are dimensions in directions orthogonal to each other. The cross section of the support may be oval, rhombic, or rectangular. The width of the cross section of the support is larger than the thickness of the cross section of the support in any of these cross sections.

  The plurality of supports have a plurality of first supports whose natural frequencies are the first natural frequencies and a plurality of second natural frequencies whose respective natural frequencies are different from the first natural frequencies. Includes second support.

  According to this configuration, when the three-dimensional object is vibrated at the first frequency, the frequency of the first support approaches the first natural frequency and the first support resonates. As a result, a large stress is generated in the tip portion of the first support, and the tip portion of the first support breaks. On the other hand, when the three-dimensional object is vibrated at the second frequency different from the first frequency, the frequency of the second support approaches the second natural frequency, and the second support resonates. As a result, a large stress is generated in the tip portion of the second support, and the tip portion of the second support breaks. Therefore, all or almost all of the first support and the second support can be cut from the metal member only by vibrating the three-dimensional object at two frequencies.

  When the plurality of supports include the plurality of first supports and the plurality of second supports, the breaking step includes a first support at a first frequency at which the first support vibrates at the first natural frequency. By vibrating the three-dimensional object by a removing device, the first support step of breaking the first support, and the second support vibrates at the second natural frequency before or after the first breaking step. A second breaking step of breaking the second support by vibrating the three-dimensional object by the second support removing device at the second frequency may be included. The second support removing device may be the same device as the first support removing device or may be a different device.

  The natural frequencies of the plurality of supports are equal to each other.

  According to this configuration, when the three-dimensional object is vibrated at a certain frequency, the frequency of the support approaches the natural frequency and the support resonates. As a result, a large amount of stress is generated on the tip of the support, and the tip of the support breaks. Therefore, all the supports or almost all the supports can be cut from the metal member only by vibrating the three-dimensional object at one frequency.

  The metal member includes a hollow portion provided with a hole opened on an outer surface of the metal member and a cavity extending from the hole to the inside of the metal member, and the support is disposed in the hollow portion. ing.

  According to this structure, since the support is arranged in the hollow portion of the metal member, it is difficult to bring the tool for cutting the support into contact with the support. However, each support can be cut only by vibrating the three-dimensional object without using such a tool. Then, the cut support can be discharged to the outside of the cavity through the hole of the hollow portion opened on the outer surface of the metal member. This allows the support to be removed from the metal member.

  The support further includes a notch opening on an outer surface of the support, and a dimension in the stacking direction from a tip portion of the support to the notch in the stacking direction is smaller than a maximum value of a diameter of the hole.

  According to this configuration, the notch opening in the outer surface of the support is provided in the support. When the support cut from the metal member collides with the metal member, stress concentration occurs at the notch. If this stress exceeds the strength of the support, the support will break at the notch. The dimension in the stacking direction from the tip of the support to the notch is smaller than the maximum value of the diameter of the hole. Therefore, the support cut from the metal member can be cut into a plurality of pieces shorter than the diameter of the hole. This allows the cut support to be efficiently discharged through the hole in the hollow portion.

  The support further includes a notch opening at an outer surface of the support.

  According to this configuration, the notch opening in the outer surface of the support is provided in the support. When the support cut from the metal member collides with the metal member, stress concentration occurs at the notch. If this stress exceeds the strength of the support, the support will break at the notch. Therefore, the support cut from the metal member can be cut into a plurality of shorter pieces.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a metal member which can reduce the burden required for support removal can be provided.

It is a block diagram which shows the outline of the manufacturing system of the metal member which concerns on one Embodiment of this invention. It is a schematic diagram which shows the three-dimensional molded object made from metal manufactured by the manufacturing system shown in FIG. FIG. 2A is an external view of the three-dimensional molded item viewed in the direction of arrow IIA shown in FIG. FIG. 2B is a cross-sectional view of the three-dimensional object along the line IIB-IIB shown in FIG. FIG. 2C is an external view of the three-dimensional modeled object viewed in the direction of the arrow IIC shown in FIG. It is a schematic diagram which shows the support (1st support) provided in the three-dimensional molded item shown in FIG. FIG. 3A is a side view of the support seen in the direction of arrow IIIA shown in FIG. FIG. 3B is a front view of the support seen in the direction of arrow IIIB shown in FIG. FIG. 3C is a plan view of the support seen in the direction of arrow IIIC shown in FIG. It is sectional drawing which shows an example of the cross section of the support which follows the IV-IV line shown in FIG.3(b). It is sectional drawing which shows the other example of the cross section of the support which follows the IV-IV line shown in FIG.3(b). It is a schematic diagram which shows an example of a support removal apparatus. It is sectional drawing which shows the state which the 1st support was cut|disconnected from the metal member. It is sectional drawing which shows the state which the 1st support bent by the notch and the 2nd support was cut|disconnected from the metal member. It is sectional drawing which shows the state in which the 2nd support was bent by the notch. It is sectional drawing which shows the state in which the support cut|disconnected was discharged|emitted from the metal member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an outline of a manufacturing system 1 for a metal member 13 according to an embodiment of the present invention. FIG. 1 shows the metal member 13 and the support 12 that are different in shape from the actual shape for easy understanding.

  The manufacturing system 1 for the metal member 13 includes a personal computer 2 that creates 3D data (so-called 3D model) of the three-dimensional object 11, and a metal solid based on the 3D data of the three-dimensional object 11 created by the computer 2. The 3D printer 3 that manufactures the modeled object 11 and the support removing device 4 that removes the support 12 from the three-dimensional modeled object 11 made of metal manufactured by the 3D printer 3 are included.

  When manufacturing the metal member 13, 3D modeling is performed using the computer 2 to create 3D data of the three-dimensional object 11. After that, based on the 3D data of the three-dimensional model 11, the 3D printing that causes the 3D printer 3 to manufacture the metallic three-dimensional model 11 is performed. After that, the three-dimensional model 11 is manually or automatically conveyed to the support removing device 4 and the support removing device 4 is caused to remove the support 12. Thereby, the metal member 13 is manufactured.

  In the computer 2, slicing for dividing the 3D data of the three-dimensional object 11 into a plurality of layers parallel to the stacking direction DL (vertical direction), and instruction data (so-called G, which defines the modeling order of each layer generated by slicing). The software (so-called slicer) that creates and creates the code is installed. The function of the slicer may be included in the 3D CAD software or the 3DCG software installed in the computer 2.

  The 3D printer 3 combines all the layers included in the three-dimensional model 11 in the stacking direction DL in this order from the modeling stage 3a side in accordance with the G code. The 3D printer 3 manufactures each layer included in the three-dimensional structure 11 by selective laser sintering in which only a specific part of the metal powder layer is sintered by laser irradiation. Selective laser sintering is a type of additive manufacturing. In the case of additive manufacturing, the 3D printer 3 may manufacture the three-dimensional object 11 made of metal by a method other than the selective laser sintering.

  The three-dimensional model 11 is made of a metal material such as iron. The three-dimensional model 11 includes a metal member 13 having an overhang portion 14 and a support 12 that supports the overhang portion 14. The 3D data of the metal member 13 may be created by 3D CAD software or 3DCG software installed in the computer 2, or may be created by a 3D scanner. The 3D data of the support 12 is automatically added to the 3D data of the metal member 13. This addition may be performed by slice software, 3D CAD software or 3DCG software.

  FIG. 2 is a schematic view showing a three-dimensional object 11 made of metal, which is manufactured by the manufacturing system 1 shown in FIG. FIG. 3 is a schematic diagram showing the support 12 (first support 12a) provided on the three-dimensional model 11 shown in FIG.

  FIG. 2A is an external view of the three-dimensional model 11 as viewed in the direction of arrow IIA shown in FIG. FIG. 2B is a cross-sectional view of the three-dimensional model 11 taken along line IIB-IIB shown in FIG. FIG. 2C is an external view of the three-dimensional model 11 as viewed in the direction of arrow IIC shown in FIG. FIG. 3A is a side view of the support 12 viewed in the direction of arrow IIIA shown in FIG. FIG. 3B is a front view of the support 12 viewed in the direction of arrow IIIB shown in FIG. FIG. 3C is a plan view of the support 12 seen in the direction of arrow IIIC shown in FIG.

  As shown in FIG. 2B, the metal member 13 includes a hollow portion 15 that forms a cavity 18. The cavity 18 may connect two holes that open on the outer surface of the metal member 13, or may extend from one hole that opens on the outer surface of the metal member 13 to the inside of the metal member 13. It may be closed at. FIG. 2B shows the former example. When the metal member 13 is, for example, a cylinder head included in an engine component, the hollow portion 15 corresponds to a water jacket that guides cooling water that cools the engine.

  The hollow portion 15 includes a first hole 17 opened on the outer surface of the metal member 13, a second hole 19 opened on the outer surface of the metal member 13, and a cavity 18 extending from the first hole 17 to the second hole 19. Including and The first hole 17 may have a circular shape, an elliptical shape, or another shape. The same applies to the second hole 19. The area of the first hole 17 is smaller than the area of the second hole 19. The area of the first hole 17 may be equal to the area of the second hole 19 or may be larger than the area of the second hole 19.

  The cavity 18 of the hollow portion 15 is formed by a cylindrical inner peripheral surface 16 that surrounds the center line L1 of the cavity 18. The inner peripheral surface 16 of the hollow portion 15 is continuous over the entire circumference in the circumferential direction of the hollow portion 15 (direction around the center line L1). The cavity 18 includes a first passage 18a extending from the first hole 17 toward the second hole 19, a second passage 18b extending from the first passage 18a toward the second hole 19 and a second passage 18b. It includes a third passage 18c extending toward the second hole 19 and a fourth passage 18d extending from the third passage 18c to the second hole 19. The diameter of the second passage 18b is larger than the diameter of the third passage 18c.

  The plurality of supports 12 are arranged in the hollow portion 15, that is, in the cavity 18. In FIG. 2B, the number of the supports 12 is reduced to facilitate understanding, but in reality, more supports 12 are arranged in the hollow portion 15. Further, in FIG. 2B, the support 12 is arranged only in the second passage 18b and the third passage 18c, but the support 12 is also arranged in at least one of the first passage 18a and the fourth passage 18d. Good.

  Each support 12 is integral with the metal member 13 and is made of the same metal material as the metal member 13. Each of the supports 12 is in contact with the metal member 13 only by the two tip portions of the support 12 in the stacking direction DL, that is, the upper end portion 12u and the lower end portion 12L of the support 12. Each support 12 extends in the stacking direction DL from a lower portion of the inner peripheral surface 16 of the hollow portion 15 to an upper portion of the inner peripheral surface 16 of the hollow portion 15. The overhang portion 14 is provided on the ceiling portion of the hollow portion 15, that is, above the inner peripheral surface 16 of the hollow portion 15. Therefore, the overhang portion 14 is supported by the plurality of supports 12.

  The support 12 may be solid or hollow. More specifically, the entire support 12 may be solid or hollow, or a solid portion and a hollow portion may be provided in the support 12. If the support 12 is entirely hollow, or if the hollow portion is provided in the support 12, the support 12 may have a mesh-shaped cross section or an annular cross section surrounding the internal space. You may have. FIG. 4A shows the former example, and FIG. 4B shows the latter example.

  As shown in FIGS. 3A, 3B, and 3C, the upper end 12u of the support 12 is thinner than the center 12c of the support 12 in the stacking direction DL. That is, the outer peripheral length of the upper end portion 12u of the support 12 is shorter than the outer peripheral length of the central portion 12c of the support 12. Similarly, the lower end portion 12L of the support 12 is thinner than the central portion 12c of the support 12 in the stacking direction DL.

  The thickness of the support 12, that is, the length of the outer periphery of the support 12 increases as it approaches the central portion 12c of the support 12. The upper end 12u of the support 12 may be thicker or thinner than the lower end 12L of the support 12, or may have the same thickness as the lower end 12L of the support 12. The maximum value of the outer diameter of the support 12 (the width W1 shown in FIGS. 4A and 4B) is smaller than the maximum value Φ1 of the diameter of the first hole 17 (see FIG. 2A), and the maximum value of the second hole 19 is smaller. It is smaller than the maximum diameter Φ2 (see FIG. 2C).

  The cross-sectional area of the support 12 (the area of the cross section orthogonal to the stacking direction DL) increases continuously or stepwise as it approaches the central portion 12c of the support 12 in the stacking direction DL. 3A and 3B show an example in which the cross-sectional area of the support 12 continuously increases. The cross-sectional area of the tip portion of the support 12 (the upper end portion 12u or the lower end portion 12L of the support 12) is smaller than the cross-sectional area of other portions of the same support 12. In this case, the cross-sectional area of the upper end 12u of the support 12 may be larger or smaller than the cross-sectional area of the lower end 12L of the same support 12, or may be equal to the cross-sectional area of the lower end 12L of the same support 12.

  4A and 4B show an example in which the support 12 has a rhombus-shaped cross section. The support 12 may have a cross section having such a shape at any position in the stacking direction DL, or may have a cross section having such a shape only at a specific position. The support 12 may have an elliptical or rectangular cross section, or may have a cross section other than these. Regardless of the cross section of the support 12, the width W1 of the cross section of the support 12 is larger than the thickness T1 of the cross section of the support 12. All the supports 12 are arranged such that the thickness direction Dt of the supports 12 is parallel or substantially parallel to the axial direction Da of the cavity 18 (direction of the center line L1 of the cavity 18).

  The plurality of supports 12 include a plurality of first supports 12a arranged in the second passage 18b and a plurality of second supports 12b arranged in the third passage 18c. The first support 12a is longer than the second support 12b in the stacking direction DL. The length of the second support 12b in the stacking direction DL is larger than the maximum value Φ1 of the diameter of the first hole 17 and larger than the maximum value Φ2 of the diameter of the second hole 19. Therefore, the length of the first support 12a in the stacking direction DL is larger than the maximum value Φ1 of the diameter of the first hole 17 and larger than the maximum value Φ2 of the diameter of the second hole 19.

  The first support 12a has a first natural frequency. The second support 12b has a second natural frequency. That is, each element (shape, cross-sectional area, size, etc.) that determines the natural frequency of the first support 12a is set so that the natural frequency of the first support 12a becomes the first natural frequency. Similarly, each element that determines the natural frequency of the second support 12b is set so that the natural frequency of the second support 12b becomes the second natural frequency. The first natural frequency is lower than the second natural frequency.

  Each support 12 includes a plurality of notches that open at the outer surface of the support 12. As shown in FIG. 3A, the first support 12a includes an upper notch 20u and a lower notch 20L arranged at different positions in the stacking direction DL. As shown in FIG. 2B, the second support 12b includes a central notch 20c arranged between the upper end 12u of the second support 12b and the lower end 12L of the second support 12b in the stacking direction DL. The central portion 12c of the first support 12a in the stacking direction DL is arranged between the upper notch 20u and the lower notch 20L in the stacking direction DL.

  The dimension D1 in the stacking direction DL from the upper end 12u of the first support 12a to the upper notch 20u is smaller than the maximum diameter Φ1 of the diameter of the first hole 17 and smaller than the maximum diameter Φ2 of the diameter of the second hole 19. small. Similarly, the dimension D3 in the stacking direction DL from the lower end 12L of the first support 12a to the lower notch 20L is smaller than the maximum value Φ1 of the diameter of the first hole 17 and the maximum diameter of the second hole 19. It is smaller than the value Φ2. Further, the dimension D2 in the stacking direction DL from the upper notch 20u to the lower notch 20L is smaller than the maximum value Φ1 of the diameter of the first hole 17 and smaller than the maximum value Φ2 of the diameter of the second hole 19.

  The dimension D4 in the stacking direction DL from the upper end 12u of the second support 12b to the central notch 20c is smaller than the maximum value Φ1 of the diameter of the first hole 17 and smaller than the maximum value Φ2 of the diameter of the second hole 19. small. Similarly, the dimension D5 in the stacking direction DL from the lower end 12L of the second support 12b to the central notch 20c is smaller than the maximum value Φ1 of the diameter of the first hole 17, and the maximum value of the diameter of the second hole 19. It is smaller than Φ2.

  Next, the removal of the support 12 will be described.

  FIG. 5 is a schematic diagram showing an example of the support removing device 4. FIG. 6A is a sectional view showing a state in which the first support 12 a is cut from the metal member 13. FIG. 6B is a cross-sectional view showing a state in which the first support 12 a is broken by the notch and the second support 12 b is cut from the metal member 13. FIG. 6C is a cross-sectional view showing a state in which the second support 12b is broken at the notch. FIG. 6D is a cross-sectional view showing a state where the cut support 12 is discharged from the metal member 13.

  As shown in FIG. 5, the support removing device 4 that removes the support 12 from the three-dimensional object 11 includes a holder 31 that holds the three-dimensional object 11, and a vibration motor that vibrates the three-dimensional object 11 held by the holder 31. And 32. When removing all the supports 12 from the metal-made three-dimensional object 11 manufactured by the 3D printer 3 (see FIG. 1 ), the three-dimensional object 11 is attached to the holder 31. In this state, the vibration motor 32 vibrates the three-dimensional object 11 in a constant vibration direction Db.

  Specifically, the vibration motor 32 vibrates the three-dimensional object 11 at the first frequency and then vibrates the three-dimensional object 11 at the second frequency. The first frequency is the natural frequency of the first support 12a, that is, the frequency at which the first support 12a vibrates at the first natural frequency. The second frequency is the natural frequency of the second support 12b, that is, the frequency at which the second support 12b vibrates at the second natural frequency. The first frequency is lower than the second frequency.

  When the three-dimensional model 11 is vibrated, the first support 12a bends, and the central portion 12c of the first support 12a is displaced in the vibration direction Db with respect to the upper end 12u and the lower end 12L of the first support 12a. As a result, stress is generated in the upper end 12u and the lower end 12L of the first support 12a. Similarly, when the three-dimensional model 11 is vibrated, the central portion 12c of the second support 12b is displaced in the vibration direction Db with respect to the upper end portion 12u and the lower end portion 12L of the second support 12b, and the upper end portion of the second support 12b. Stress is generated in 12u and the lower end 12L.

  Since the thickness T1 of the cross section of the first support 12a is smaller than the width W1 of the cross section of the first support 12a, the first support 12a is easily bent in the thickness direction Dt of the first support 12a. Similarly, since the thickness T1 of the cross section of the second support 12b is smaller than the width W1 of the cross section of the second support 12b, the second support 12b is easily bent in the thickness direction Dt of the second support 12b. The thickness direction Dt of each support 12 matches or substantially matches the vibration direction Db of the three-dimensional model 11. Therefore, the first support 12a and the second support 12b can be stably deformed in the vibration direction Db.

  When the frequency of the first support 12a approaches the first natural frequency, the first support 12a resonates, and the stress generated at the upper end 12u and the lower end 12L of the first support 12a increases. The strength of the upper end 12u and the lower end 12L of the first support 12a is lower than the strength of the other parts of the first support 12a. As shown in FIG. 6A, when this stress exceeds the strength of the upper end 12u of the first support 12a, the upper end 12u of the first support 12a breaks. Similarly, when this stress exceeds the strength of the lower end 12L of the first support 12a, the lower end 12L of the first support 12a breaks.

  The natural frequency of the second support 12b (second natural frequency) is higher than the natural frequency of the first support 12a (first natural frequency). When the support removing device 4 vibrates the three-dimensional object 11 at the first frequency, both the first support 12a and the second support 12b vibrate, but the natural frequencies of the first support 12a and the second support 12b. Are different from each other, the second support 12b does not resonate. Therefore, as shown in FIG. 6A, even after the first support 12 a is cut from the metal member 13, the second support 12 b is bonded to the metal member 13.

  When the support removing device 4 changes the frequency of the three-dimensional model 11 to the second frequency, the second support 12b resonates, and the stress generated in the upper end 12u and the lower end 12L of the second support 12b increases. The strength of the upper end 12u and the lower end 12L of the second support 12b is lower than the strength of other parts of the second support 12b. As shown in FIG. 6B, when this stress exceeds the strength of the upper end 12u of the second support 12b, the upper end 12u of the second support 12b breaks. Similarly, when this stress exceeds the strength of the lower end 12L of the second support 12b, the lower end 12L of the second support 12b breaks.

  As shown in FIG. 6B, each support 12 includes a plurality of notches 20u, 20c, 20L that open at the outer surface of the support 12. When the three-dimensional model 11 is vibrated, each support 12 is deformed and stress is generated in the notches 20u, 20c, 20L. After the support 12 is cut from the metal member 13, the support 12 repeatedly collides with the metal member 13 due to the vibration of the three-dimensional structure 11. Therefore, stress is generated in the notches 20u, 20c, and 20L even after the support 12 is cut. . As shown in FIGS. 6B and 6C, the support 12 is folded at the notches 20u, 20c, and 20L after being cut from the metal member 13. As a result, the support 12 cut from the metal member 13 can be cut into a plurality of pieces that are shorter than the diameters of the first hole 17 and the second hole 19.

  After the three-dimensional object 11 is vibrated at the first frequency and the second frequency and all the supports 12 are cut from the metal member 13, as shown in FIG. 6D, the cut supports 12 are cut into the first holes 17. And, it is discharged from the cavity 18 of the hollow portion 15 through at least one of the second holes 19. The support 12 may be discharged by flowing a fluid such as air or water into the cavity 18 or by tilting and shaking the metal member 13. If necessary, the metal member 13 may be subjected to machining such as drilling or polishing after the cut support 12 is discharged from the metal member 13.

  As described above, in the present embodiment, the metal three-dimensional model 11 is manufactured by stacking and coupling a plurality of layers in the stacking direction DL. The three-dimensional model 11 includes a metal member 13 having an overhang portion 14 and a plurality of supports 12 that support the overhang portion 14. The support 12 is a part formed of the same metal material as the metal member 13 and integral with the metal member 13. The support 12 is in contact with the metal member 13 only at the tip of the support 12 (the upper end 12u or the lower end 12L of the support 12) in the stacking direction DL. The cross-sectional area of this tip portion is smaller than the cross-sectional area of other portions of the support 12. In other words, the strength of the tip of the support 12 is lower than the strength of other parts of the support 12.

  When the three-dimensional model 11 is vibrated, each support 12 vibrates together with the metal member 13, and stress is generated in each part of the support 12. The tip of the support 12 has the lowest strength in the support 12. When the stress generated at the tip of the support 12 exceeds the strength of the tip of the support 12, the tip of the support 12 breaks. That is, the most fragile tip portion of the support 12 breaks first, and the support 12 is cut from the metal member 13. Therefore, each support 12 can be cut from the metal member 13 only by vibrating the entire three-dimensional model 11. This can reduce the load required to remove the support 12.

  In this embodiment, the thickness T1 of the cross section of the support 12 is smaller than the width W1 of the cross section of the support 12. That is, the support 12 is thin in the thickness direction Dt and easily bends in the thickness direction Dt of the support 12. When the three-dimensional model 11 is vibrated, the support 12 alternately repeats deformation and restoration in the thickness direction Dt. As a result, a repeated load whose size and direction change regularly can be applied to the support 12, and the tip of the support 12 can be reliably broken.

  In the present embodiment, when the three-dimensional model 11 is vibrated at the first frequency, the frequency of the first support 12a approaches the first natural frequency, and the first support 12a resonates. As a result, a large stress is generated in the tip portion of the first support 12a, and the tip portion of the first support 12a is broken. On the other hand, when the three-dimensional model 11 is vibrated at a second frequency different from the first frequency, the frequency of the second support 12b approaches the second natural frequency, and the second support 12b resonates. As a result, large stress is generated in the tip portion of the second support 12b, and the tip portion of the second support 12b is broken. Therefore, all or almost all of the first support 12a and the second support 12b can be cut from the metal member 13 only by vibrating the three-dimensional object 11 at two frequencies.

  In this embodiment, since the support 12 is arranged in the hollow portion 15 of the metal member 13, it is difficult to bring a tool for cutting the support 12 into contact with the support 12. However, each support 12 can be cut only by vibrating the three-dimensional model 11 without using such a tool. Then, the cut support 12 can be discharged to the outside of the cavity 18 through the hole of the hollow portion 15 opening on the outer surface of the metal member 13. Thereby, the support 12 can be removed from the metal member 13.

  In the present embodiment, the support 12 is provided with notches 20u, 20c, 20L that open on the outer surface of the support 12. When the support 12 cut from the metal member 13 collides with the metal member 13, stress concentration occurs in the notches 20u, 20c, 20L. When this stress exceeds the strength of the support 12, the support 12 breaks at the notches 20u, 20c, 20L. The dimensions D1, D2, D4, and D5 in the stacking direction DL from the tip (upper end or lower end) of the support 12 to the notches 20u, 20c, and 20L are smaller than the maximum value Φ1 of the diameter of the first hole 17. , Smaller than the maximum value Φ2 of the diameter of the second hole 19. Therefore, the support 12 cut from the metal member 13 can be cut into a plurality of pieces that are shorter than the diameters of the first hole 17 and the second hole 19. As a result, the cut support 12 can be efficiently discharged through the hole of the hollow portion 15.

Other Embodiments The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made.

  For example, the metal member 13 may be an engine component other than the cylinder head or may be a component other than the engine component.

  The support 12 may be arranged outside the hollow portion 15. For example, the support 12 may extend from the modeling stage 3a (see FIG. 1) to the overhang portion 14. That is, the lower end 12L of the support 12 may be in contact with the modeling stage 3a instead of the metal member 13.

  Notches 20u, 20c, 20L may be omitted from support 12.

  One of the width and the thickness of the support 12 may be constant, and the other of the width and the thickness may be decreased as the tip of the support 12 is approached.

  The natural frequencies of all the supports 12 may be equal to each other or may be different from each other. In the former case, all the supports 12 or almost all the supports 12 can be resonated and cut from the metal member 13 only by vibrating the three-dimensional model 11 at one frequency.

  As long as the upper end 12u and the lower end 12L of the support 12 are fractured, the frequency of the three-dimensional structure 11 does not have to be the frequency at which the support 12 resonates.

  Two or more of all the configurations described above may be combined.

  In addition, various design changes can be made within the scope of the matters described in the claims.

1: Manufacturing system 2: Computer 3: 3D printer 3a: Modeling stage 4: Support removing device 11: Three-dimensional model 12: Support 12a: First support 12b: Second support 12u: Upper end 12c of support: Center part of support 12L: Lower end part 13 of support: Metal member 14: Overhang part 15: Hollow part 16: Inner peripheral surface 17 of hollow part: First hole 18: Cavity 18a: First passage 18b: Second passage 18c: Third Passage 18d: Fourth passage 19: Second hole 20u: Upper notch 20c: Central notch 20L: Lower notch 31: Holder 32: Vibration motors D1 to D5: Dimension Da: Axial direction Db: Vibration direction DL: Lamination Direction Dt: Thickness direction L1: Cavity center line T1: Support cross-section thickness W1: Support cross-section width Φ1: Maximum diameter of first hole Φ2: Maximum diameter of second hole

Claims (8)

A method for manufacturing a metal member, comprising a modeling step of manufacturing a three-dimensional object made of metal by additive manufacturing by bonding while stacking a plurality of layers in a stacking direction,
The three-dimensional model includes a metal member having an overhang portion, and a plurality of supports that support the overhang portion and that are integral with the metal member,
The support is in contact with the metal member only at the tip of the support in the stacking direction,
A method for manufacturing a metal member, wherein a cross-sectional area of a tip portion of the support is smaller than a cross-sectional area of another portion of the support.   The method for manufacturing a metal member according to claim 1, further comprising a breaking step of breaking the support by vibrating the three-dimensional object with a support removing device.   The method for manufacturing a metal member according to claim 1, wherein at least a part of the support has a cross section whose width is larger than its thickness.   The plurality of supports have a plurality of first supports whose natural frequencies are the first natural frequencies and a plurality of second natural frequencies whose respective natural frequencies are different from the first natural frequencies. The method for manufacturing a metal member according to claim 1, further comprising a second support.   The method for manufacturing a metal member according to claim 1, wherein the plurality of supports have equal natural frequencies. The metal member includes a hole that is opened on the outer surface of the metal member, and a cavity that extends from the hole to the inside of the metal member, and includes a hollow portion.
The said support is a manufacturing method of the metal member as described in any one of Claims 1-5 arrange|positioned in the said hollow part. The support further includes a notch opening at an outer surface of the support,
The method for manufacturing a metal member according to claim 6, wherein a dimension in the stacking direction from a tip portion of the support to the notch in the stacking direction is smaller than a maximum value of a diameter of the hole.   The method for manufacturing a metal member according to claim 1, wherein the support further includes a notch opening at an outer surface of the support.

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